Marathon blowouts

[roned2]

We just started a two week trip into New York. 30 minutes from home our tire on the passenger side of the trailer shredded. We waited for tire repair service and got the spare on. One hour later the other tire shredded on the drivers side. Both tires were inflated to between 60 and 65 PSI. One tow truck driver said it might have been the excessive heat of the road that day. The tire guy who replaced the spare said the tire should have been able to withstand that. This was our first trip of the season. Any ideas. Both tires were about 3 years old with about 12000 miles on them. We have some damage to the plumbing system so I would like to know how to avoid this. Bad luck?